zrana is right. But if you're planning to use a microSD card to expand the phone's storage (by partition), I don't think this is a good idea. This might make your phone's performance bad if the microSD card starts to fail.

If you're pertaining to RAM there are apps like AParted (link). But again, if your microSD card fails, it'll just mess up your phone.

Hey Adelene, you can use external memory card to increase memory of phone.